A display substrate of an OLED display panel includes a thin film transistor array and a luminous element array, wherein the thin film transistor array includes a plurality of thin film transistors, and the luminous element array includes an anode layer, a cathode layer and a luminous layer that is provided between the anode layer and the cathode layer. The anode layer includes a plurality of anodes, and the anodes are connected with drains of the thin film transistors in a one-to-one correspondence.
The cathode layer is generally formed by sputtering a transparent material such as Indium Tin Oxide (ITO) or evaporating a transparent material having a good reflectivity above the luminous layer. In a case where the cathode layer is formed by sputtering ITO, the luminous layer is easily to be damaged, and luminous efficiency of the OLED display panel is reduced.
As described above, the cathode layer may also be formed by evaporating a transparent material having a good reflectivity. However, the cathode layer formed in such manner often has a large resistance, and a large IR drop will be present when displaying, eventually degrading the image quality of the display panel.
Thus, how to prevent the image quality of the display panel from being degraded due to the large IR drop in the cathode becomes a technical problem having to be solved urgently.